In this video, i want to talk about nitrogen pressure, testing and leak detection. It's a pretty simple seaming subject, but it's an area that a lot of mistakes are made because again the nitrogen pressure test is the place that we confirm that we don't have any leaks, especially after we've brazed in all of our copper connections made all of our Flared connections or other types of mechanical connections, and so it's really important that we pass or fail so that way we know if we have any additional leaks. It's a super important part of a clean, dry and tight system, which is what allows a new air conditioning. Refrigeration system to last a really long time, all right step, one before you're, going to pressure test anything or do any further leak detection.

You want to make sure that there are not any leaks at your schrader course now again depending on. If this is a brand new system or if you've made a significant repair or whether you're walking up to a system for the first time, this is going to vary how this is going to go. But if you walk up to a system that has any signs of oil around the schraders you're going to want to go ahead and address those right away. So, generally speaking, the best bet would just be to go ahead and pull out the old schraders and replace them to eliminate them, as a potential problem also make sure that your caps have seals any hoses you're going to connect for your nitrogen pressure test should have Nice new seals in them, and then another thing to keep in mind is when you are bubble testing a best practice in bubble.

Testing is to put a cap over the port with no seal in it and then spray bubbles on the cap rather than spraying bubbles. Straight into the schrader port, if you get soap in there, obviously we don't want that in the system, so putting a cap over it with no seal will kind of act as a dust cap but will still allow anything to leak out and that's just kind of A good practice, if you are going to bubble test them, you can also bubble test your actual hoses or any of your connections after you're, under pressure before you're, going to pressure test, you want to purge nitrogen through the system. Now that's different than flowing nitrogen flowing nitrogen is done at a super super low pressure, something like three to five scfh purging can be done at a much higher pressure. This image here is showing the western nitrogen regulator that has the purge mode right on it.

But, generally speaking, i'm going to purge it's something like 100 psi and that's just purging through one side and allowing it to flow out the other side, and this just ensures that we displace as much air and oxygen as we can before. We pressurize. Then we're going to attach pressure probes to each side of the system, i'm showing here using two crts core remover tools. With the pressure probes on the sides, you can use a different strategy using a manifold if you like, just keep in mind that the more connections that you place into the system, the more likely those connections themselves, are going to be.

The leak point also commonly with manifolds the actual gauge where it attaches to the manifold body, is a possible leak point. So you're going to want to make sure all of those are leak free as well. Next, you're going to pressurize the equipment with 250 to 600 psig of nitrogen. That's typical! Again! You want to follow the manufacturer's recommendations.

Generally speaking, if you are going to be pressurizing, the low side of the system you're going to use the low side test pressure, if you're working on something like a vrf or vrv system, that's where these higher pressures would come in and those are recommended by some Manufacturers, once you get up to your desired pressure range, then you're going to valve off the nitrogen from the system. This is a nice way you can use crts because they give you nice easy ball valves. The good quality ones that are designed for vacuum also hold really nicely with their design. You also do want to make sure that you are not leaking out of the end and again that's where you can once again use that technique use a cap with no seal in it, cap it and then bubble test it around that cap, rather than spraying bubbles.

Right in the end of a crt just to make sure that you're not leaking there, especially when you're using these higher pressures like 500 or 600 psi next you're going to let it stand typically for 30 to 60 minutes, that's going to be a very standard residential Type of test pressure, time frame, if you're doing something like a vrf or vrv system, where you have much higher internal volumes a lot of piping and you have to make sure you do not have leaks, then sometimes they're going to have you sit 24, even 48 Hours, so that's why i mentioned you know: do it according to manufacture specifications, if you see any drop, that's where you want to start over again start over and make sure that you test everything either way, i'm going to use soap bubbles on any field fabricated joints, Especially any braised joints or any flares that we made while you're under this pressure test and just checking for small micro bubbles. If you are going to perform an electronic leak detection, you would have had to put a little bit of trace refrigerant in first and again that varies quite a bit. There is no standard guideline. I can give you of how much to add.

That's one of the common questions we get, how much trace refrigerant. Do you add um you're not going to add a lot? Generally speaking on a residential system, it's going to be well under a pound and you're just going to put it in the vapor phase. It's just so that way you can trace and find it with an electronic leak detection. Once you have passed or failed now, you release the nitrogen.

You proceed with whatever else you're going to do. If it's a new system or you've replaced a component. The next step would be the vacuum generally. If it does fail, then you again start over use your soap bubbles or use your electronic leak detection methods.

Now one thing i also want to mention is using a nitrogen pressure calculator if there is a significant change in temperature. So let's just use an example. Let's say we put in 300 psi, which would be a very standard pressure to use if the temperature started off at 90 degrees and then the average temperature dropped to 70 degrees over the period of time of the pressure test, my pressure would drop to 288 psig. Again, you also see here i calculated the atmospheric pressure at sea level, so you would also need to calculate that, and so it is normal for nitrogen pressure to change within the system if there is a significant change in temperature, but keep in mind that temperature change Relates to both the inside and outside if you've got a split system and the evaporators inside and the condenser is outside and you're pressurizing everything that's going to be an average of everything both inside and outside, and that can be a tricky business and so just recognizing Primarily that there will be a change in pressure if there's a change in temperature generally, if you're doing a 30 minute to an hour type of pressure test, there's not going to be a big enough change that it would matter if you're doing a 24 hour or 48 hours, something really long like that, there could be a significant difference and using a nitrogen pressure.

Calculator can really help. So that's it. That's some of our best practices for nitrogen pressure. Testing make sure you use a good quality regulator, make sure you have no leaks.

Try to keep it as simple as possible and monitor that pressure on both sides. Another thing to keep in mind that i've mentioned in previous videos is, if you are pressurizing on the liquid line and you're watching your suction side come up, which is what i generally suggest put it in the liquid line. Watch the suction side come up if you're doing higher pressures and you have a hard shutoff. Txv you'll hit a point where it will stop flowing through because that hard shut off txv closes off, and so that's something to think about.

And when you get to that point, you would have to pressurize from both sides in order to get up to those higher pressures. If you are pushing through a hard shut off txv all right, that's it thanks for watching we'll catch you on the next video thanks for watching our video, if you enjoyed it and got something out of it, if you wouldn't mind hitting the thumbs up button to Like the video subscribe to the channel and click, the notifications bell to be notified when new videos come out, hvac school is far more than a youtube channel. You can find out more by going to hvacrschool.com, which is our website and hub for all of our content, including tech tips, videos, podcasts and so much more. You can also subscribe to the podcast on any podcast app of your choosing.

You can also join our facebook group if you want to weigh in on the conversation yourself thanks again for watching you.